U.S. officials say documents taken from military spy agencies by former National Security Agency contractor Edward Snowden could, if disclosed, compromise the operations or embarrass countries that do not wish to be seen as cooperating with the United States. (Uncredited/AP)

Snowden, U.S. officials said, took tens of thousands of military intelligence documents, some of which contain sensitive material about collection programs against adversaries such as Iran, Russia and China. Some refer to operations that in some cases involve countries not publicly allied with the United States.

The process of informing officials in capital after capital about the risk of disclosure is delicate. In some cases, one part of the cooperating government may know about the collaboration while others — such as the foreign ministry — may not, the officials said. The documents, if disclosed, could compromise operations, officials said.

The notifications come as the Obama administration is scrambling to placate allies after allegations that the NSA has spied on foreign leaders, including German Chancellor Angela Merkel. The reports have forced the administration to play down operations targeting friends while also attempting to preserve other programs that depend on provisional partners. In either case, trust in the United States may be compromised.

“It is certainly a concern, just as much as the U.S. collection [of information on European allies] being put in the news, if not more, because not only does it mean we have the potential of losing collection, but also of harming relationships,” a congressional aide said.

The Office of the Director of National Intelligence is handling the job of informing the other intelligence services, the officials said. ODNI declined to comment.

In one case, for instance, the files contain information about a program run from a NATO country against Russia that provides valuable intelligence for the U.S. Air Force and Navy, said one U.S. official, who requested anonymity to discuss an ongoing criminal investigation. Snowden faces theft and espionage charges.

“If the Russians knew about it, it wouldn’t be hard for them to take appropriate measures to put a stop to it,” the official said.

Snowden lifted the documents from a top-secret network run by the Defense Intelligence Agency and used by intelligence arms of the Army, Air Force, Navy and Marines, according to sources, who spoke on the condition of anonymity to discuss sensitive matters.

Snowden took 30,000 documents that involve the intelligence work of one of the services, the official said. He gained access to the documents through the Joint Worldwide Intelligence Communications System, or JWICS, for top-secret/sensitive compartmented information, the sources said.

The material in question does not deal with NSA surveillance but primarily with standard intelligence about other countries’ military capabilities, including weapons systems — missiles, ships and jets, the officials say.

Although Snowden obtained a large volume of documents, he is not believed to have shared all of them with journalists, sources say. Moreover, he has stressed to those he has given documents that he does not want harm to result.

“He’s made it quite clear that he was not going to compromise legitimate national intelligence and national security operations,” said Thomas Drake, a former NSA executive who visited Snowden in Moscow this month. Snowden separately told Drake and a New York Times reporter that he did not take any documents with him to Russia. “There’s a zero percent chance the Russians or Chinese have received any documents,” Snowden told the Times in an online interview last week.

Indeed, Drake said, Snowden made clear in their conversation that he had learned the lessons of prior disclosures, including those by an Army private who passed hundreds of thousands of diplomatic cables to the anti-secrecy organization WikiLeaks, which posted them in bulk online. “It’s telling,” Drake said, “that he did not give anything to WikiLeaks.”

Nonetheless, the military intelligence agencies remain fearful, officials said. The NSA in recent months has provided them with an accounting of the documents it believes Snowden obtained.

Intelligence officials said that they could discern no pattern to the military intelligence documents taken and that Snowden appeared to have harvested them at random. “It didn’t seem like he was targeting something specific,” the U.S. official said.

The notifications are reminiscent of what the State Department had to do in late 2010 in anticipation of the release of hundreds of thousands of sensitive diplomatic cables by WikiLeaks. The department feared that embarrassing details in some of the cables would lead to tension in relations between the United States and other countries.

In the case of WikiLeaks, the State Department had a number of months to assess the potential impact of the cables’ release and devise a strategy, former State Department spokesman P.J. Crowley said.

“I’m not sure there were that many startling surprises in the cables,” he said. But there was damage on a country-by-country basis, he said.

For instance, some of the cables reflected unfavorably on ­then-Libyan leader Moammar Gaddafi, alleging that he feared flying over water and almost never traveled without his “voluptuous blonde” Ukrainian nurse. “All of a sudden we found there were some unsavory guys following” then-U.S. Ambassador to Libya Gene Cretz, Crowley said. “We brought him home for consultations and did not send him back.”

“But broadly speaking,” Crowley said, “relationships are guided by interests, rather than personalities, and, over time, interests carry the day.”

The fundamental issue is one of trust, officials said. “We depend to a very great extent on intelligence-sharing relationships with foreign partners, mostly governments — or, in some cases, organizations within governments,” a second U.S. official said. “If they tell us something, we will keep it secret. We expect the same of them. [If that trust is undermined,] these countries, at a minimum, will be thinking twice if they’re going to share something with us or not.”

Snowden has instructed the reporters with whom he has shared records to use their judgment to avoid publishing anything that would cause harm. “I carefully evaluated every single document I disclosed to ensure that each was legitimately in the public interest,” he told the Guardian newspaper. “There are all sorts of documents that would have made a big impact that I didn’t turn over, because harming people isn’t my goal. Transparency is.”

It is those documents that may not be subject to journalistic vetting or may be breached by hackers that worry some intelligence officials. Snowden is known to have given documents in any quantity to only three journalists: The Post’s Barton Gellman, independent filmmaker Laura Poitras and former Guardian columnist Glenn Greenwald.

So far, Drake said, no such documents have been released. Snowden’s disclosures about the NSA have prompted a global debate about the proper scope and purpose of U.S. espionage — against its own and other countries’ citizens.

“I consider that a good thing,” Drake said.

Ellen Nakashima is a national security reporter for The Washington Post. She focuses on issues relating to intelligence, technology and civil liberties.

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